Surgical suture having an ultrasonically formed tip, and apparatus and method for making same

ABSTRACT

An apparatus and method for ultrasonically forming a surgical suture tip from a length of unfinished surgical suture material. The apparatus includes a first tipping die having a first face for contacting a portion of the length of unfinished surgical suture material. A second tipping die having a second face is also provided. At least one mechanical actuator is provided for moving the first face of the first tipping die toward the second face of the second tipping die. A second actuator vibrates at least one of the first and second tipping dies at an ultrasonic frequency of about 15 KHz to 70 KHz. The method of ultrasonically forming a suture tip comprises the positioning a surgical suture between the first face of the tipping die and the second face of the tipping die then vibrating the dies at an appropriate frequency.

FIELD OF THE INVENTION

The present invention is directed to systems for processing strings andyarns. More particularly, the present invention is directed to automatedsystems for forming surgical suture tips through the use of ultrasonicwelding.

BACKGROUND OF THE INVENTION

Various automated systems for forming and cutting surgical suture tipsexist or are known in the art. In one such machine, means forsimultaneously advancing in parallel at least six separate strands ofsuture material, and six independent tensioners for maintainingrespective parallel portions of each of the six strands at a presettension are provided. Once a predetermined length of suture material hasbeen advanced by the advancing means, a horizontal heater bar(positioned perpendicular to the six suture strands) is actuated by anelectronically controlled solenoid which moves a planar heater bar intocontact with one side of the suture strands for a predetermined dwelltime. Once the predetermined dwell time has elapsed, the solenoidretracts the heater bar to its original position, and the heat exposed(or heat-stiffened) section of suture material is advanced to a cuttingstation. At the cutting station, the heat-stiffened section of suturematerial is cut at its midpoint, thereby producing a suture with twostiffened ends. Other mechanisms for forming and cutting surgical suturetips are shown in U.S. Pat. Nos. 4,832,025, 4,806,737 and 5,226,336 toCoates. The system described in the Coates patents uses convective ornon-contact heating to form suture tips.

Known systems for forming and cutting surgical suture tips suffer fromseveral drawbacks. First, such systems typically use heat to stiffen thesurgical suture tips. Since the unfinished surgical suture material usedby such systems is often coated, the heat applied during the tippingprocess may melt the coating. Once it has melted, the coating from theunfinished surgical suture material often adheres to the tippingmachine, thereby compromising the machine's performance. Anotherdrawback of known systems for forming and cutting surgical suture tipsis that such systems typically produce a suture tip which lacks asubstantially uniform cross-section. In addition, such systems areundesirable in that they typically cut the suture tip in an imprecisemanner, thereby leaving a cut end which may be irregular or distorted inshape. From a manufacturing standpoint, suture tips having non-uniformcross-sections and/or irregular or distorted cut ends are undesirablebecause, among other things, such sutures are difficult to insert intoneedles. Finally, known systems which use heat to stiffen surgicalsuture tips are undesirable because such systems cannot be used withsutures formed from silk.

It is therefore an object of the present invention to provide a systemfor forming surgical suture tips which system does not use heat informing the suture tips and which may be used to fuse silk.

It is a further object of the present invention to provide a surgicalsuture having a welded core which facilitates the easy insertion of thesuture tip into a needle.

It is a further object of the present invention to provide an automatedsystem and method for manufacturing surgical sutures having tips withwelded cores.

It is a still further object of the present invention to provide anautomated system and method for making surgical sutures with tips havingprecisely cut ends.

These and other objects and advantages of the invention will become morefully apparent from the description and claims which follow or may belearned by the practice of the invention.

SUMMARY OF THE INVENTION

The present invention is directed to a multifilament surgical suturehaving a body portion and a tip portion which is adjacent to the bodyportion. The surgical suture is formed of a plurality of filaments. Thetip portion has a tip length, a tip cross-section perpendicular to thetip length, and a tip core positioned at a center of the tipcross-section and along the tip length. The filaments positioned at thetip core are ultrasonically fused together.

In accordance with a further aspect, the present invention is directedto an apparatus for ultrasonically forming a surgical suture tip from alength of unfinished surgical suture material. The apparatus includes afirst tipping die having a first face for contacting a portion of thelength of unfinished surgical suture material. A second tipping diehaving a second face is also provided. At least one mechanical actuatoris provided for moving the first face of the first tipping die towardthe second face of the second tipping die. A second actuator vibrates atleast one of the first and second tipping dies at an ultrasonicfrequency of about 15 KHz to 70 KHz.

In accordance with a still further aspect, the present invention isdirected to a method for ultrasonically forming a surgical suture tipfrom a length of unfinished surgical suture material. The length ofunfinished surgical suture material is positioned at a location betweena first face of a first tipping die and a second face of a secondtipping die. After the positioning step, the surgical suture tip isformed by vibrating at least one of the first and second tipping dies atan ultrasonic frequency of about 15 KHz to 70 KHz.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the manner in which the above-recited and other advantagesand objects of the invention are obtained and can be appreciated, a moreparticular description of the invention briefly described above will berendered by reference to a specific embodiment thereof which isillustrated in the appended drawings. Understanding that these drawingsdepict only a typical embodiment of the invention and are not thereforeto be considered limiting of its scope, the invention and the presentlyunderstood best mode thereof will be described and explained withadditional specificity and detail through the use of the accompanyingdrawings.

FIG. 1 is a schematic diagram showing a machine for ultrasonicallyforming and cutting surgical sutures, in accordance with a preferredembodiment of the present invention.

FIG. 2 is a side view of a suture tipping station formed from a pair ofopposing tipping dies one of which is in its retracted position, inaccordance with a preferred embodiment the present invention.

FIG. 3 is a side view of the suture tipping station of FIG. 2, whereinone of the tipping dies in the station is in its extended position.

FIG. 4 is an enlarged view of a portion of the suture tipping stationshown in FIG. 2.

FIG. 5 is an enlarged view of a portion of the suture tipping stationshown in FIG. 3.

FIG. 6 shows a cross-sectional view of a length of surgical suturematerial which has been ultrasonically fused at its core, in accordancewith a preferred embodiment of the present invention.

FIGS. 7 and 8 show side views of opposing tipping dies forultrasonically forming surgical suture tips, in accordance withalternative preferred embodiments of the present invention.

FIG. 9 is a cross-sectional view of a moving clamp shown in its closedstate for grasping and advancing surgical suture material, in accordancewith a preferred embodiment of the present invention.

FIG. 10 is a cross-sectional view showing the moving clamp of FIG. 9 inits open state, in accordance with a preferred embodiment of the presentinvention.

FIG. 11 is a cross-sectional view of a stationary clamp shown in itsclosed state for grasping surgical suture material, in accordance with apreferred embodiment of the present invention.

FIG. 12 is a cross-sectional view showing the stationary clamp of FIG.11 in its open state, in accordance with a preferred embodiment of thepresent invention.

FIG. 13 is an isometric view of a system for tensioning a length ofsurgical suture material, in accordance with a preferred embodiment ofthe present invention.

FIG. 14 is an isometric view of an optical detection system fordetecting knots in surgical suture material passing through the system,in accordance with a preferred embodiment of the present invention.

FIG. 15 is a further isometric view showing a knot positioned betweenthe optical source and the optical detector of the knot detection systemof FIG. 14, in accordance with a preferred embodiment of the presentinvention.

FIG. 16 is a cross-sectional view of FIG. 15, showing a knot positionedbetween the optical source and the optical detector of the knotdetection system of FIG. 14, in accordance with a preferred embodimentof the present invention.

FIG. 17 is a side view of a suture tipping station formed of opposingcircular tipping dies, in accordance with an alternative preferredembodiment of the present invention.

FIG. 18 is a cross-sectional view of the suture tipping station shown inFIG. 17.

FIG. 19 is a side view of a suture tipping and cutting station formed ofopposing circular tipping and cutting dies, in accordance with a furtheralternative preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Overall System Operation

Referring now to FIG. 1, there is shown a schematic diagram showing amachine 10 for ultrasonically forming and cutting surgical sutures, inaccordance with a preferred embodiment of the present invention. Acontinuous length of unfinished surgical suture material 110 is suppliedto machine 10 from a supply spool 100 having unfinished surgical suturematerial 110 wound thereon. Unfinished surgical suture material 110 fromsupply spool 100 is initially advanced through a tensioning assembly 200for creating a tension in the unfinished surgical suture material, andthen through a knot detector system 300 for detecting whether a knot ispresent in any unfinished surgical suture material 110 passing throughknot detector system 300. After passing through the knot detector system300, the unfinished surgical suture material is advanced to a tippingstation 400, where a predetermined length of the unfinished surgicalsuture material 110 is ultrasonically formed into a length of surgicalsuture tip material. After the ultrasonically formed surgical suture tipmaterial is formed in station 400, the suture tip material is advancedto a cutting station 450 (e.g., an automated scissor or guillotinecutter) where the suture tip material is cut, thereby yielding afinished surgical suture having a body portion formed of unfinishedsurgical suture material 110 and an ultrasonically formed tip portionterminating with a cut end.

As explained more fully below, the unfinished surgical suture material110 from supply spool 100 is advanced through machine 10 by a movingclamp 500 which is coupled to a linear actuator 550 for driving themoving clamp 500 between a starting or home position 510 on one side ofthe cutting station 450 and an end position 512 on the other side of thecutting station 450. Moving clamp 500 has a grasping (or closed) stateshown in FIG. 9, and a non-grasping (or open) state shown in FIG. 10. Inaccordance with instructions received from a controller 800, the movingclamp 500 selectively grasps and pulls the unfinished surgical suturematerial 110 through machine 10 in order to facilitate the manufactureof the finished surgical sutures. In addition to advancing unfinishedsurgical suture material through the machine, the moving clamp 500functions to initially position and align the unfinished surgical suturematerial 110 within the tipping station 400.

During operation of the machine 10, the moving clamp 500 initiallygrasps or closes on the unfinished surgical suture material 110 at thehome position 510. Next, while the moving clamp 500 remains in itsgrasping or closed state, the linear actuator 550 drives the movingclamp 500 from its home position 510 to the end position 512. As thelinear actuator 550 drives moving clamp 500 from its home position 510to its position 512, the moving clamp 500 pulls a length of theunfinished surgical suture material 110 through the station 400 andthrough a stationary clamp 600 positioned adjacent to the end position512. Like the moving clamp 500, the stationary clamp 600 has a grasping(or closed) state which is shown in FIG. 11, and a non-grasping (oropen) state shown in FIG. 12. As the linear actuator 550 drives themoving clamp 500 from home position 510 to end position 512, thestationary clamp 600 is in its open state. After the moving clampreaches its end position 512, the stationary clamp 600 grasps or closeson the unfinished surgical suture material 110 positioned within thestationary clamp 600. The positions of cutting station 450 andstationary clamp 600 along the length of machine 10 may be adjusted inorder to facilitate the creation of sutures with different lengths.

As illustrated in FIGS. 2-3, the combined tipping and cutting station400 includes a pair of opposing tipping dies 402, 404. The tipping die402 has both an open state (shown in FIG. 2) and a closed state (shownin FIG. 3). When, as described above, the linear actuator 550 drives themoving clamp 500 from home position 510 to end position 512, the tippingdie 402 in station 400 is in its open position. After the moving clampreaches its end position 512 and the stationary clamp 600 has grasped orclosed on the unfinished surgical suture material 110 positioned withinthe stationary clamp 600, the tipping die 402 moves from its open (orretracted) state to its closed (or extended) state in order tofacilitate the ultrasonic forming of a predetermined length of surgicalsuture tip material. As described in greater detail below in connectionwith FIGS. 2-5, while the tipping die 402 is in its closed state, atleast one of the tipping dies 402, 404 vibrates at an ultrasonicfrequency in order to form a length of surgical suture tip material.After the tipping die 402 has been in its closed state for apredetermined period of dwell time (i.e., weld time plus hold time),tipping die 402 moves from its closed to its open state, therebyyielding a length of tipped surgical suture material positioned betweendies 402, 404. While this length of tipped surgical suture materialremains positioned between dies 402, 404, a further length of tippedsurgical suture material (previously tipped by station 400) which ispositioned within cutting station 450 is severed by station 450, therebyyielding a tipped surgical suture with a cut end.

While the surgical suture material positioned at station 400 is beingtipped, the moving clamp 500 opens and releases the surgical suturematerial within its grasp and, with the tipping die 402 still in itsclosed state, the linear actuator 550 drives the moving clamp 500 fromits end position 512 to its home position 510 where the moving clampcloses on a next piece of unfinished surgical suture material 110. Next,after the tipping of the surgical suture material at station 400 iscompleted and the tipping die 402 is in its open state, the suturematerial at station 450 is cut. Thereafter, the stationary clamp 600releases the surgical suture material within its grasp (i.e., a finishedsurgical suture with a cut tip), the linear actuator 550 drives theclosed moving clamp back to its end position 512, and the processdescribed above is then preferably repeated in order to manufacturefurther finished surgical sutures. Since the tensioning assembly 200exerts a tensioning force on the surgical suture material 110 positionedwithin machine 10, it is important for the moving clamp 500 to grasp orclose on the surgical suture material prior to the time that thestationary clamp 600 opens, in order to prevent the tensioning assembly200 from pulling the trailing end of the surgical suture material cut bystation 450 in a reverse direction when the tipped surgical suturematerial is severed by station 450.

The unfinished surgical suture material 110 used in machine 10 formanufacturing the finished sutures may consist of any thermoplasticbraided suture material such as, for example, a polyester braided suturematerial, or a polyamide or polyolyfin suture material. In addition, theunfinished surgical suture material 110 used in machine 10 may consistof silk or linen material, in which case, machine 10 may be used toultrasonically fuse silk or linen tips. Alternatively, the unfinishedsurgical suture material 110 used in machine 10 may consist of nylonmaterial, in which case, machine 10 may be used to ultrasonically fusenylon tips. In a preferred embodiment of the present invention describedmore fully below, the unfinished surgical suture material 110 used inmachine 10 is a braided suture material formed of a polyethyleneterephthalate, such as that sold by Ethicon, Inc. under the trademarkEthibond® Excel®. In a preferred embodiment, a Simatic model TI1435controller manufactured by Siemens is used to implement controller 800.An operator interface is preferably coupled to the controller 800.

Operation of Tipping Dies

As mentioned above, after the moving clamp 500 has reached its endposition 512, the tipping dies 402, 404 in the tipping station 400operate to ultrasonically form a predetermined length of surgical suturetip material from the unfinished surgical suture material 110 positionedwithin the station 400. During the operation of the tipping dies 402,404, the unfinished surgical suture material 110 is suspended in analigned and fixed positioned within station 400 by the stationary clamp600 which is positioned on one side of station 400, and by the pulley514 which is positioned on an opposing side of station 400. In addition,during the operation of the tipping dies 402, 404, the unfinishedsurgical suture material 110 suspended within station 400 is maintainedat a preset tension by tensioning system 200.

FIGS. 2 and 3 show two views of the tipping station 400. Each of theviews illustrates the position of the tipping dies 402, 404 at aparticular point during a suture tipping cycle. Referring nowspecifically to FIG. 2, there is shown a side view of station 400,wherein the tipping die 402 is in its retracted or open position. FIG. 2shows the position of tipping die 402 when the moving clamp 500 firstreaches its end position 512. After the moving clamp 500 has reached itsend position 512, a cylinder 406 (controlled by controller 800) drivesthe tipping die 402 from its retracted to its extended position. Inmoving the tipping die 402 between its retracted and extended positions,cylinder 406 drives tipping die 402 along the axis indicated by arrows408. FIG. 3 shows the position of the tipping die 402 after the cylinder406 has moved tipping die 402 to its extended position. As the tippingdie 402 is moved to its extended position, a cross-sectional portion ofthe suture material 110 suspended within station 400 is contacted byface 402a of tipping die 402 and face 404a of tipping die 404. In apreferred embodiment of the present invention, the cylinder 406 causestipping die faces 402a and 404a to apply pressure to (or squeeze) theouter surfaces of the suture material 110 positioned between dies 402and 404. In this preferred embodiment, about 25 PSI of pressure isapplied to the outer surfaces of the suture material when die faces 402aand 404a "close-on" or squeeze the suture material positioned in station400.

After faces 402a and 404a have been brought together and the tippingdies 402, 404 have "closed on" the unfinished surgical suture material110 as shown in FIG. 3, one or both of the tipping dies 402, 404 vibrateat an ultrasonic frequency for a predetermined weld time in order toform a suture tip. In the preferred embodiment, tipping die 402 remainsfixed in position during a dwell time (i.e., a weld time followed by ahold time) when the tipping dies 402, 404 have closed-on the unfinishedsurgical suture material 110, and an ultrasonic horn 412 which isconnected to tipping die 404 vibrates tipping die 404 along the axis 410at a frequency of 15 KHz to 70 KHz and an amplitude of 0.0001 to 0.010inches for about 0.050 to 10.0 seconds in order to form the suture tip.In a still further preferred embodiment, horn 412 vibrates tipping die404 at a frequency of 20 KHz to 40 KHz at an amplitude of 0.004 inchesfor 200 ms during the suture tipping step. During the dwell time whenthe tipping dies 402, 404 have closed-on the unfinished surgical suturematerial 110, the vibrating of tipping die 404 against tipping die 402causes filaments within the interior or core 112 (shown in FIG. 6) ofthe unfinished surgical suture material 110 (as well as filaments on theexterior surface 114 of the suture material) to fuse or weld together,thereby forming a length of surgical suture tip material between dies402, 404. Thereafter, at the end of the dwell time, the cylinder 406opens the tipping die 402 by bringing it back to its initial retractedposition. In the preferred embodiment, a transducer 414 which is coupledto horn 412 by a booster 416 is used for vibrating horn 412. Booster 416functions to control the amplitude of the ultrasonic vibrations. Afinished surgical suture formed with an ultrasonically fused suture tipas described above has been found to exhibit a tensile strength alongthe suture tip that is about 75% to 84% of the tensile strength of thebody portion (i.e., the untipped portion) of the finished suture.

The tipping parameters used to form an ultrasonically fused tip varydepending upon the diameter of the unfinished suture material 110 beingsupplied to machine 10. Set forth in Table I below are the preferredtipping parameters used for ultrasonically forming tips on differentsizes of an unfinished braided suture material formed of a polyethyleneterephthalate, such as that sold by Ethicon, Inc. under the trademarkEthibond® Excel®. Also set forth in Table I below for each size sutureis the preferred pressure to be applied to the exterior surfaces of thesuture material by tipping dies 402, 404 when the tipping dies first"close-on" the unfinished suture material, the preferred frequency thattipping die 404 should vibrate during the ultrasonic tipping process,and the preferred dwell times during which the tipping dies 402, 404should remain closed on (and vibrate against) the unfinished suturematerial 110 during the ultrasonic tipping process.

                  TABLE I    ______________________________________    SIZE    0        2/0      3/0    4/0    5/0    ______________________________________    Tipping Die            80       25       25     15     5    Pressure    (in PSI)    Tipping Die            15-70    15-70    15-70  15-70  15-70    Vibration    Frequency    (in KHz)    Tipping Die            0.900-   0.400-   0.100- 0.025- 0.025-    Weld Time            10.0     5.0      5.0    2.0    2.0    (in seconds)    Tipping Die            0.100-   0.100-   0.100- 0.100- 0.100-    Hold Time            0.500    0.500    0.500  0.500  0.500    (in seconds)    ______________________________________

In the preferred embodiment of the present invention, tipping dies 402,404 are made of steel, and are coated with a non-stick substance such asTiN, Teflon® or Nedox®, in order to facilitate the release of the suturematerial from the tipping dies 402, 404 when such dies are opened.Although in the preferred embodiment described above, the tipping dies402 and 404 were a particular shape, it will be understood by thoseskilled in the art that tipping dies defining other shapes, such asthose shown in FIGS. 7 and 8, may also be used to ultrasonically formsuture tips in accordance with the present invention. Similarly,although the ultrasonically tipped suture shown in FIG. 6 has a circularcross-section, it will be understood by those skilled in the art thatultrasonically tipped sutures having cross-sections of other shapes(e.g., polygonal) may be formed in accordance with the present inventionby varying the shape and orientation of the tipping dies employed.

Suture Tensioning System

Referring now to FIG. 13, there is shown an isometric view of the system200 for tensioning a length of surgical suture material 110, inaccordance with a preferred embodiment of the present invention. System200 includes a tensioning spool 202 having a width, a weight and acircular perimeter 204 perpendicular to the width of the spool. Thetensioning spool 202 has a groove 206 in its perimeter 204 for receivingthe surgical suture material 110. Tensioning system 200 also includes atrack 208 formed from a pair slots 208a, 208b extending in parallelalong the length of the track 208. Track 208 and slots 208a, 208b arepreferably positioned along a purely vertical axis, although, inalternate embodiments (not shown), track 208 and slots 208a, 208b may bealigned along an axis that includes both horizontal and verticalcomponents. The slots 208a, 208b function to receive and guide thetensioning spool 202 along the length of track 208 during operation ofsystem 200. The length of the track 208 is preferably alignedperpendicularly to the width of the tensioning spool 202.

During operation of the system 200, the tensioning spool 202 issuspended vertically within slots 208a, 208b by the surgical suturematerial 110. While the tensioning spool 202 is suspended verticallywithin slots 208a, 208b by the surgical suture material 110, the weightof the tensioning spool 202 exerts a corresponding tensioning force onthe suture material 110 equal to the weight of spool 202. In order tovary the tension exerted on the suture material 110 during operation ofsystem 200, additional weights 210 may be added or removed from a spoolarm extending from the center of spool 202. The tension exerted on thesuture material 110 during operation of system 200 preferably representsthe minimum tension necessary to prevent the suture material 110 fromgetting "bunched-up" as it is pulled through machine 10 by moving clamp500.

When the moving clamp 500 described above is in its grasping state andmoves from its home position 510 to its end position 512, suturematerial 110 suspended in the slots 208a, 208b is drawn forwardlythrough station 400 of machine 10. As the suture material is drawnforwardly through the machine by the moving clamp 500, the tensioningspool 202 is pulled upwardly within slots 208a, 208b. However,regardless of the vertical position of the spool 202 within the slots208a, 208b, the tension exerted on the suture material 110 by system 200will be the constant and equal to the weight of spool 202. An opticalsensor 212, coupled to controller 800, is provided for determiningwhether the pulling action of the moving clamp 500 has caused the spool202 to be drawn upwardly within the track 208 past the height of thesensor 212. When optical sensor 212 detects that the tensioning spool202 has been pulled upwardly past the location of the sensor 212,controller 800 causes a motor (not shown) coupled to the supply spool100 to unwind unfinished surgical suture material 110 from the supplyspool 100. As further unfinished surgical suture material 110 is unwoundfrom the supply spool 100, the tensioning spool 202 moves downwardlywithin the track 208. In the preferred embodiment, controller 800continues to unwind unfinished surgical suture material 110 from thesupply spool 100 until the tensioning spool 202 falls below the level ofoptical sensor 212.

An optical sensor 214 is provided at the bottom of track 208 fordetermining whether there has been a break in the surgical suturematerial 110 or a loss of tension in the suture material within machine10. Since, during normal operation, the tensioning spool 202 should notfall below the level of optical sensor 212, a break in suture material110 or a loss of suture tension within machine 10 will be signaled bysensor 214 if the sensor determines that the tensioning spool 202 hasfallen to the level of the sensor 214.

Knot Detection System

Referring now to FIGS. 14 and 15, there are shown two isometric views ofan optical detection system 300 for detecting knots in surgical suturematerial 110 passing through system 300, in accordance with a preferredembodiment of the present invention. Knot detector system 300 includesan optical light source 302 for directing a plane of light 304 at anoptical light detector 306 when surgical suture material 110 ispositioned between the optical light source 302 and the optical lightdetector 306. The optical light source 302 is preferably formed of aplurality of optical fibers 302a having their terminating ends alignedalong the optical plane 304. Controller 800 is coupled to an output ofthe optical light detector 306 for processing the signals output bydetector 306 and determining whether a knot exists in the suturematerial 110 positioned between the light source 302 and light detector306. More particularly, by comparing a magnitude of a shadow 308 cast onthe optical light detector 306 by the suture material 110 against apredetermined threshold, controller 800 determines whether or not a knotexists in the suture material 110 positioned between the light source302 and light detector 306. In a preferred embodiment, the predeterminedthreshold used in this comparison corresponds to a magnitude of a shadow308a cast on the optical light detector 306 by an unknoted cross-sectionof suture material 110. In a still further preferred embodiment,controller 800 will determine that a knot exists in the suture material110 passing through system 300 only if the magnitude of the shadow caston light detector 306 by suture material 110 exceeds by at least 30% themagnitude of a shadow 308a cast on the optical light detector 306 by anunknoted cross-section of suture material 110.

Extended Length Suture Mode

Although, in the process described above, machine 10 was used tomanufacture a finished surgical suture having a length that was lessthan length of the linear actuator 550, machine 10 may also be used inan extended length suture mode, described below, in order to makefinished surgical sutures which are longer than linear actuator 550.During operation of the machine 10 in the extended length suture mode,the moving clamp 500 initially grasps or closes on the unfinishedsurgical suture material 110 at the home position 510. Next, while themoving clamp 500 remains in its grasping or closed state, the linearactuator 550 drives the moving clamp 500 from its home position 510 tothe end position 512. As the linear actuator 550 drives moving clamp 500from its home position 510 to its position 512, the moving clamp 500pulls a length of the unfinished surgical suture material 110 throughthe tipping station 400, cutting station 450 and through the stationaryclamp 600. After the moving clamp reaches its end position 512, thestationary clamp 600 grasps or closes on the unfinished surgical suturematerial 110 positioned within the stationary clamp 600. The movingclamp 500 then releases the unfinished surgical suture material 110 inits grasp. Next, while the moving clamp is in its open or non-graspingstate, the linear actuator 550 drives the moving clamp 500 from its endposition 512 to its home position 510, where the moving clamp 500 againgrasps or closes on the unfinished surgical suture material 110 at thehome position 510. After the moving clamp 500 grasps the unfinishedsurgical suture material 110 at the home position 510 for the secondtime, the stationary clamp 600 opens. Thereafter, while the moving clamp500 remains in its grasping or closed state and the stationary clamp 600remains in its open state, the linear actuator 550 again drives themoving clamp 500 from its home position 510 to the end position 512.After the moving clamp 500 reaches its end position 512 for the secondtime, the stationary clamp 600 again grasps or closes on the unfinishedsurgical suture material 110 positioned within the stationary clamp 600.

After the unfinished surgical suture material 110 has been "pulledtwice" by the moving clamp 500 as described in the paragraph above, thedies 402, 404 in the tipping station 400 function as described above toultrasonically form a length of surgical suture tip material positionedwithin the station 400. Following the cutting of this suture tipmaterial at station 450, the stationary clamp 600 releases the surgicalsuture material within its grasp. As the stationary clamp opens andreleases the previously grasped surgical suture material, a finishedsurgical suture having an ultrasonically formed and cut tip results.Since the moving clamp 500 pulled the suture material 110 two timesconsecutively before the tipping station 400 formed the suture tip, theresulting finished surgical suture produced by the extended lengthsuture mode may have a length which is greater than the length of thelinear actuator 550.

Continuous Process Using Circular Tipping Dies

Referring now to FIGS. 17 and 18, there are shown side andcross-sectional views of an alternative suture tipping station 400aformed of opposing circular tipping dies 440, 450 for continuouslytipping unfinished surgical suture material 110a, in accordance with analternative preferred embodiment of the present invention. Tipping die440 contains a notch 403 around a portion of its perimeter, and tippingdie 450 contains a corresponding groove 405 positioned about itsperimeter. In the preferred embodiment of station 400a, notch 403 issized such that pressure is applied to the exterior surface of suturematerial 110a when suture material 110a is between notch 403 and thelower end of groove 405. Tipping dies 440, 450 are coupled to mechanicalactuators (not shown) which continually rotate the dies 440, 450 in thedirection of the arrows shown in FIG. 17. During rotation of the tippingdies 440, 450, an ultrasonic horn (also not shown) vibrates tipping die440 against tipping die 450 at a frequency of 15 KHz to 70 KHz (andpreferably 20 KHz to 40 KHz) and an amplitude of 0.0001 to 0.010 inchesin order to continuously form suture tip material. Station 400a may besubstituted for station 400 in FIG. 1, in order to configure machine 10to continuously produce surgical sutures with ultrasonically formedtips, in accordance with the present invention.

Referring now to FIG. 19, there is shown a side view of a suture tippingand cutting station 400b formed of opposing circular tipping and cuttingdies 440a, 450 for continuously tipping and cutting unfinished surgicalsuture material 110, in accordance with a further alternative preferredembodiment of the present invention. Die 440a is substantially the sameas die 440, except that die 440a includes a cutting point 403b forcutting a suture tip end portion during the rotation of die 440a against450. Station 400b functions substantially the same as station 400a,except that station 400b may be used to both form and cut suture tips ina continuous manner. Since the cutting performed by station 400b isaccomplished using a cutting point 403b which vibrates at an ultrasonicfrequency, a suture tip is simultaneously both cut and sealed by station400b. In addition, the ultrasonic cutting action of point 403b yields acut suture tip with a lead angle which facilitates the insertion of thecut suture tip into a drilled needle. Although in the preferredembodiment of station 400b, dies 440a and 450 function to both tip andcut surgical suture material 110, it will be understood by those skilledin the art that two separate pairs of circular dies may be employed inseries to respectively perform the tipping and cutting operations.

Furthermore, it is to be understood that although the present inventionhas been described with reference to a preferred embodiment, variousmodifications, known to those skilled in the art, may be made to thestructures and process steps presented herein without departing from theinvention as recited in the several claims appended hereto.

What is claimed is:
 1. An apparatus for ultrasonically forming asurgical suture tip from a length of unfinished surgical suturematerial, comprising:(A) a tipping station having a first tipping diehaving a first face for contacting a portion of said length of saidunfinished surgical suture material; a second tipping die having asecond face at least one mechanical actuator for moving said first faceof said first tipping die toward said second face of said second tippingdie wherein said first and second tipping die faces contact and applypressure to the outer surface of the unfinished suture material; and asecond actuator for vibrating at least one of said first and secondtipping dies at an ultrasonic frequency of about 15 kHz to 70 kHz; (B) acutting station for cutting said portion of said surgical suture; (C) amoving clamp for advancing the surgical suture material from the tippingstation to the cutting station; and (D) a stationary clamp for holdingthe suture in a stationary position, located adjacent to the cuttingstation.
 2. The apparatus of claim 1, wherein said second actuator isprovided for vibrating at least one of said first and second tippingdies at an amplitude of 0.0001 to 0.010 inches.
 3. The apparatus ofclaim 2, wherein said second actuator is coupled to said second tippingdie and is formed of an acoustic horn.
 4. The apparatus of claim 1,wherein said at least one mechanical actuator is formed from a cylindercoupled to said first tipping die for moving said first tipping die fromits open to its closed position.